1. Field of the Invention
The present invention relates to a detector for detecting the position of a mark, an imprint apparatus, and an article manufacturing method.
2. Description of the Related Art
The imprint technique makes it possible to transfer nanoscale micropatterns, and is beginning to be put into practical use as one nanolithography technique for the mass-production of magnetic recording media and semiconductor devices. In the imprint technique, a mold having a micropattern is used as an original to form the micropattern on a substrate such as a silicon wafer or glass plate by using an apparatus such as an electron-beam exposure apparatus. The micropattern is formed by coating the substrate with a resin, and curing the resin while the pattern of the mold is pressed against the substrate with the resin being sandwiched between them. Imprint techniques presently put into practical use are the heat cycle method and photo-curing method. The heat cycle method forms a pattern by increasing the fluidity of a thermoplastic resin by heating the resin to a temperature equal to or higher than the glass transition temperature, pressing a mold against a substrate with the resin having a high fluidity being sandwiched between them, and releasing the mold from the resin after cooling. The photo-curing method forms a pattern by pressing a mold against a substrate with an ultraviolet-curing resin being sandwiched between them, curing the resin by irradiating it with ultraviolet light in this state, and releasing the mold from the cured resin. In the heat cycle method, the transfer time increases due to temperature control, and the dimensional accuracy decreases due to temperature changes. However, the photo-curing method has no such problems. Presently, therefore, the photo-curing method is advantageous in the mass-production of nanoscale semiconductor devices. Japanese Patent No. 4185941 discloses a method of aligning a mold with a shot on a substrate by detecting a mark formed on the mold and a substrate mark formed in the shot by using a scope.